Households are facing their fourth day without a water supply as companies were told by the regulator that they have “fallen well short” on planning for the forecast weather.

Thames Water said it was working to remove airlocks in pipes across the London postcodes SW12, SW16, SW17 and SW18 and surrounding areas which were preventing water from flowing, adding: “We apologise for the time it is taking to restore your water.”

It sent out a series of tweets today listing locations where customers could continue to collect bottled water.

Despite our best efforts we are still having difficulties with our water supply to our customers in #SW12, #SW16, #SW17#SW18 (and surrounding areas). We are working to remove airlocks in our pipes which is stopping the water flowing. 1/3

Please do come and collect bottled water if you are experiencing no water - once again, we're very sorry for the inconvenience and completely understand your frustration. 6/6 pic.twitter.com/aRAlxHXckB

Water shortages caused by burst pipes have led to problems for thousands of properties and the closure of Jaguar Land Rover and Cadbury plants in the Midlands.

Severn Trent Water has now restored water supplies to the plants, saying it was working “round the clock” to fix problems caused by the big thaw.

A spokeswoman said: “We’re happy to say that the majority of our customers are starting to see their water returning, but some areas may still be experiencing intermittent supply as the network starts to get back to normal.

“We were working with the Jaguar Land Rover site in Solihull and Cadbury’s in Birmingham to reduce the amount of water they used yesterday. This was as a result of an unprecedented number of burst pipes in the area from the recent thaw.

“We’re pleased to confirm that the situation is now resolved and they are able to use their water as normal.”

#Watergate Day 4, just finished my morning call with @ThamesWater:- Many homes have water back.- Air in the system is causing issues in SW12/16/17/18. Releasing air must be done manually on each road.

While firms said they are doing their best to fix leaks and repair bursts amid milder conditions which followed the deep freeze of last week, the regulator has criticised some companies for an apparent planning failure.

Ofwat chief executive Rachel Fletcher criticised companies for their lack of preparation, support and communication with customers.

She said: “The ongoing water supply problems affecting the country, most particularly parts of London and the South East of England, have been deeply distressing for all those affected.

“While the recent severe freeze and thaw have undoubtedly had an impact on pipes and infrastructure, this weather was forecast in advance. A number of water companies appear to have fallen well short on their forward planning and the quality of support and communication they’ve been providing, leaving some customers high and dry.

“Everyone’s number one priority must be getting the water flowing as quickly as possible and ensuring that all customers – in particular those in vulnerable circumstances – get the support they need.

“When the taps are back on, we will take a long, hard look at what has happened here and we won’t hesitate to intervene if we find that companies have not had the right structures and mechanisms in place to be resilient enough.”

Day 4 of no water, I fear this is the beginning of some distopian demise of society, first the snow, then no water, followed by the plague which will inevitably lead to the hunger games @thameswater#haaalp

Welsh Water’s most recent update said 4,500 customers were affected, while Affinity Water, South East Water and Southern Water have all urged customers who do have running water only to use it where essential.

Firms supplied bottled water at affected sites but such was the demand that some stations temporarily ran out.

It follows criticism from Environment Minister Michael Gove last week, who warned water firms to clean up their act or face tougher regulation.

He told company bosses they had not been acting “in the public interest”, accusing some of “playing the system for the benefit of wealthy managers and owners”.